Alternative Model Organism Research Articles

A Simple Tube Escape Assay to Test Learning and Memory in Zebrafish with Minimized Habituation.

Various methods have been used in rodents to evaluate learning and memory. Although much less frequently used, the zebrafish emerges as an alternative model organism in this context. For example, it allows assessing potential behavioral deficits because of neurodevelopmental disorders or environmental neurotoxins. A variety of learning tasks have been employed in previous studies that required extensive habituation and training sessions. Here, we introduce a simpler and faster method to evaluate learning and memory of zebrafish with minimum habituation. A new apparatus, a transparent L-shaped tube, was developed in which we trained each zebrafish to swim through a long arm and measured the time to swim through this arm. We demonstrate that in this task, zebrafish could acquire both short-term (1 h) and long-term memory (4 days). We also studied learning and memory of a gene knockout (KO) zebrafish that showed social impairments related to autism. We found KO mutant zebrafish to show a quantitative impairment in habituation, learning, and memory performance compared with wild-type control fish. In conclusion, we established a novel learning apparatus and sensitive paradigm that allowed us to evaluate learning and memory of adult zebrafish that required only a brief habituation period and minimal training.

Non-Genetic-Induced Zebrafish Model for Type 2 Diabetes with Emphasis on Tools in Model Validation.

The unrelenting increase in the incidence of type 2 diabetes (T2D) necessitates the urgent need for effective animal models to mimic its pathophysiology. Zebrafish possess human-like metabolic traits and share significant genetic similarities, making them valuable candidates for studying metabolic disorders, including T2D. This review emphasizes the critical role of animal models in diabetes research, especially focusing on zebrafish as an alternative model organism. Different approaches to a non-genetic model of T2D in zebrafish, such as the glucose solution, diet-induced, chemical-induced, and combined diet-induced and glucose solution methods, with an emphasis on model validation using indicators of T2D, were highlighted. However, a significant drawback lies in the validation of these models. Some of these models have not extensively demonstrated persistent hyperglycemia or response to insulin resistance and glucose tolerance tests, depicted the morphology of the pancreatic β-cell, or showed their response to antidiabetic drugs. These tools are crucial in T2D pathology. Future research on non-genetic models of T2D in zebrafish must extensively focus on validating the metabolic deficits existing in the model with the same metabolic defects in humans and improve on the existing models for a better understanding of the molecular mechanisms underlying T2D and exploring potential therapeutic interventions.

Silkworm Bombyx mori as a model organism: A review

AbstractBombyx mori Linnaeus, 1758 (Lepidoptera: Bombycidae), a very important economical insect and backbone of the silk industry, is fully reliant on humans for its life cycle. It has short life span, possessing many genes having high degree of homology with human disease‐causing genes, low breeding and maintenance cost, has less ethical issues associated with it and has also got its genome fully sequenced. Because of these characteristics, it has been recognized as an alternate invertebrate model organism candidate for use in life science research. It has been successfully used as an alternative invertebrate model organism in a variety of scientific domains, including human disease models, environmental monitoring models, epigenetic models and microbial drug screening and discovery models, since the last decade. This newly emerged model has given promising results so far in its short journey and has a tremendous future prospect of establishing itself as a successful model just like the classical invertebrate models, Drosophila melanogaster Meigen, 1830 (Diptera: Drosophilidae) and Caenorhabditis elegans Maupas, 1900 (Rhabditida: Rhabditidae). The use of the silkworm B. mori as a model organism in areas linked to human health and disease is reviewed here.

Water in cosmetics and Caenorhabditis elegans as an alternative model for lifespan assessment.

Water, often considered a fundamental component of life, is the most commonly used ingredient in the formulation of dermocosmetic products, with waterless products being the exception. Dermocosmetic products can contain anywhere from 50% to 85% water, which contributes to their texture and specific characteristics. The chemical composition of water varies depending on its origin and can be categorized as highly mineralized or low mineralized. These compositions could impact the water's efficacy in anti-aging applications. In this study, the objective is evaluating the anti-aging properties of highly and low mineralized water with the model organism Caenorhabditis elegans. In this article, we employed the alternative model organism C. elegans to assess the impact of 5 branded waters, one physiological water and one ultra-pure water on the model's lifespan, using the survival medium conventionally used for C. elegans as a comparison. Waters may have either a positive or a negative impact on the C. elegans lifespan expectancy. Our results indicate that only one of the water brands we assessed (Volvic®) had a significantly positive effect on worm longevity. In contrast, we found that two other brands (Hepar® and Contrex®) had a negative impact on the later stages of the worm's adulthood. Furthermore, we demonstrated that the impact of the brand water samples on lifespan expectancy varied depending on their physicochemical composition, in particular when ion concentrations were most extreme. This study shows that the highly mineralized waters studied have a detrimental effect on the survival of C. elegans, and a preliminary test with ultra-pure water could not be completed due to its deleterious effect on the worms. This suggests the hypothesis that both highly mineralized and completely demineralized waters may not be the most suitable for skin formulations.

Mycobacterium smegmatis, a Promising Vaccine Vector for Preventing TB and Other Diseases: Vaccinomics Insights and Applications.

Mycobacterium smegmatis (M.sm) is frequently used as an alternative model organism in Mycobacterium tuberculosis (M.tb) studies. While containing high sequence homology with M.tb, it is considered non-pathogenic in humans. As such it has been used to study M.tb and other infections in vivo and more recently been explored for potential therapeutic applications. A body of previous research has highlighted the potential of using genetically modified M.sm displaying rapid growth and unique immunostimulatory characteristics as an effective vaccine vector. Novel systems biology techniques can further serve to optimize these delivery constructs. In this article, we review recent advancements in vaccinomics tools that support the efficacy of a M.sm-based vaccine vector. Moreover, the integration of systems biology and molecular omics techniques in these pioneering studies heralds a potential accelerated pipeline for the development of next-generation recombinant vaccines against rapidly developing diseases.

Intravital Microscopy of the Native Thymus

Hematopoietic Cell Transplantation (HCT) is a common treatment for patients suffering from a variety of malignant or benign diseases, reconstituting the hematopoietic system after preconditioning treatment. In patients undergoing HCT, the capacity for the thymus to produce functional T cells is inhibited due to damage from the cytotoxic preconditioning. Endogenous thymus regeneration depends on the complex relationship between thymus stromal cells (including vascular endothelial cells (EC)) and the recruitment of de novo "seeding" thymic progenitor cells (TPCs) from the regenerated bone marrow (BM). It has been demonstrated that ECs are radio-resistant, however in the context of HCT, it is not clear which type of EC (arterial, venous, or capillary) can survive following injury. Moreover, ECs are critical cells in endogenous thymic regeneration and are involved in recruiting TPCs from the BM, but functional damage to the vascular network may alter the hemodynamics and negatively impact TPC homing and thymus regeneration. Flow cytometry, immunohistochemistry, and ex vivo imaging techniques have been applied to study the thymus in preclinical mouse models since direct visualization of the native thymus in live mice was deemed impossible. Teleost fish are an alternative model organism for direct thymus observation in vivo but redundant cytokine pathways are present which do not exist in humans and mice. Unlike fish models, in mammals T cell development critically depends on the IL-7 cytokine signaling pathway. Therefore, tools to directly visualize the mouse thymus are needed in order to study functional changes to the vascular system after cytotoxic preconditioning in an immunologically relevant preclinical animal model. We hypothesize that cytotoxic preconditioning causes functional and anatomical changes in blood vessel architecture, especially cortical vasculature, that negatively impacts TPC homing and leads to long-term changes in the thymus microenvironment. In this project, we developed intravital imaging techniques to visualize the native thymus in live mice. Using our methodology, we were able to quantify the changes to the blood vessel network after sublethal irradiation (4.5 Gy). Our results showed an increase in blood vessel diameter in mice one day after receiving irradiation. We validated this result using tissue clearing and ex vivo imaging. In addition, most cortical blood flow velocity is <500 µm/s in both control and one day after sublethal irradiation, although no significant changes were observed in blood flow velocity and shear rate between the groups at this timepoint. Taken together, our study suggests that native intravital thymus imaging is a powerful technique enabling functional and anatomical characterization of the thymus vascular network. We believe, further work will help clarify the changes to the vascular system at later timepoints and in the context of higher irradiation doses. This method enables a whole new paradigm for studying thymus biology not previously possible.

OMAMO: orthology-based alternative model organism selection.

SummaryThe conservation of pathways and genes across species has allowed scientists to use non-human model organisms to gain a deeper understanding of human biology. However, the use of traditional model systems such as mice, rats and zebrafish is costly, time-consuming and increasingly raises ethical concerns, which highlights the need to search for less complex model organisms. Existing tools only focus on the few well-studied model systems, most of which are complex animals. To address these issues, we have developed Orthologous Matrix and Alternative Model Organism (OMAMO), a software and a web service that provides the user with the best non-complex organism for research into a biological process of interest based on orthologous relationships between human and the species. The outputs provided by OMAMO were supported by a systematic literature review.Availability and implementation https://omabrowser.org/omamo/, https://github.com/DessimozLab/omamo.Supplementary information Supplementary data are available at Bioinformatics online.

The utility of alternative models in particulate matter air pollution toxicology

Exposure to particulate matter (PM) air pollution increases risk of adverse human health effects. As more attention is brought to bear on the problem of PM, traditional mammalian in vivo models struggle to keep up with the risk assessment challenges posed by the countless number of unique PM samples across air sheds with limited or no toxicity information. This review examines the utility of three higher throughput, alternative, in vivo animal models in PM toxicity research: Danio rerio (zebrafish), Caenorhabditis elegans (nematode), and Drosophila melanogaster (fruit fly). These model organisms vary in basic biology, ease of handling, methods of exposure to PM, number and types of available assays, and the degree to which they mirror human biology and responsiveness, among other differences. The use of these models in PM research dates back over a decade, with assessments of the toxicity of various PM sources including traffic-related combustion emissions, wildland fire smoke, and coal fly ash. This article reviews the use of these alternative model organisms in PM toxicity studies, their biology, the various assays developed, endpoints measured, their strengths and limitations, as well as their potential role in PM toxicity assessment and mechanistic research going forward.

How do zebrafish (Danio rerio) respond to MK-801 and amphetamine? Relevance for assessing schizophrenia-related endophenotypes in alternative model organisms.

Schizophrenia pathophysiology has been associated with dopaminergic hyperactivity, NMDA receptor hypofunction, and redox dysregulation. Most behavioral assays and animal models to study this condition were developed in rodents, leaving room for species-specific biases that could be avoided by cross-species approaches. As MK-801 and amphetamine are largely used in mice and rats to mimic schizophrenia features, this study aimed to compare the effects of these drugs in several zebrafish (Danio rerio) behavioral assays. Male and female adult zebrafish were exposed to MK-801 (1, 5, and 10μM) or amphetamine (0.625, 2.5, and 10mg/L) and observed in paradigms of locomotor activity and social behavior. Oxidative parameters were quantified in brain tissue. Our results demonstrate that MK-801 disrupted social interaction, an effect that resembles the negative symptoms of schizophrenia. It also altered locomotion in a context-dependent manner, with hyperactivity when fish were tested in the presence of social cues and hypoactivity when tested alone. On the other hand, exposure to amphetamine was devoid of effects on locomotion and social behavior, while it increased lipid peroxidation in the brain. Key outcomes induced by MK-801 in rodents, such as social interaction deficit and locomotor alterations, were replicated in zebrafish, corroborating previous studies and reinforcing the use of zebrafish to study schizophrenia-related endophenotypes. More studies are necessary to assess the predictive validity of preclinical paradigms with this species and ultimately optimize the screening of potential novel treatments.

Hypoblast Formation in Bovine Embryos Does Not Depend on NANOG.

The role of the pluripotency factor NANOG during the second embryonic lineage differentiation has been studied extensively in mouse, although species-specific differences exist. To elucidate the role of NANOG in an alternative model organism, we knocked out NANOG in fibroblast cells and produced bovine NANOG-knockout (KO) embryos via somatic cell nuclear transfer (SCNT). At day 8, NANOG-KO blastocysts showed a decreased total cell number when compared to controls from SCNT (NT Ctrl). The pluripotency factors OCT4 and SOX2 as well as the hypoblast (HB) marker GATA6 were co-expressed in all cells of the inner cell mass (ICM) and, in contrast to mouse Nanog-KO, expression of the late HB marker SOX17 was still present. We blocked the MEK-pathway with a MEK 1/2 inhibitor, and control embryos showed an increase in NANOG positive cells, but SOX17 expressing HB precursor cells were still present. NANOG-KO together with MEK-inhibition was lethal before blastocyst stage, similarly to findings in mouse. Supplementation of exogenous FGF4 to NANOG-KO embryos did not change SOX17 expression in the ICM, unlike mouse Nanog-KO embryos, where missing SOX17 expression was completely rescued by FGF4. We conclude that NANOG mediated FGF/MEK signaling is not required for HB formation in the bovine embryo and that another—so far unknown—pathway regulates HB differentiation.

Starvation Stress in the Sbds -Null Zebrafish: Implications for Human Shwachman-Diamond Syndrome

Shwachman-Diamond Syndrome (SDS) is an autosomal recessive disorder characterized by exocrine pancreatic insufficiency, bone marrow dysfunction, and an increase risk of acute myeloid leukemia. Patients with SDS exhibit abnormalities in other organs, including bone, liver and immunologic and endocrine systems. Almost all cases of SDS result from biallelic mutations in the SBDS gene1. SBDS is involved in ribosomal biogenesis and stabilization of mitotic spindle microtubules2,3. Recently, it has also been shown a reduction cell proliferation and mTOR and STAT3 expression, both with an important role in cellular growth and tumorigenesis, in SDS derived leukocytes.4Genetic ablation of Sbds results in early embryonic lethality (ED 7.5) in mice5. Zebrafish provide an attractive, alternative model organism to study SDS. Genome analysis of zebrafish (Danio rerio) revealed the presence of a single sbds gene, encoding a protein 90% identical to the human orthologue.We created sbds zebrafish knockout strains that phenocopies the human Shwachman-Diamond Syndrome. Survival rate of mutants was normal at 15 days post fertilization (dpf) (100%) but decline significantly at 21 dpf (4%). Western blot analysis showed a progressive decrease of Sbds during the first 8 dpf, with total absence at 10 dpf. These results suggest that larval viability is due to maternally deposited sbds transcript and corresponding protein, which was confirmed by RT-qPCR and immunoblot at earliest developmental stages. Zebrafish sbds mutants showed neutropenia at 5 and 15 days post fertilization (dpf) but normal macrophage number and hemoglobinization. Pancreas, liver, digestive tract, and eye showed histologic evidence of atrophy at 21 dpf. Moreover, we observed an important reduction in the intestinal epithelium at 15 dpf.To further characterize effects of Sbds loss, we tested expression of genes involved in lipid metabolism (acc, ppar α , ppar γ and srbp1) and pancreatic transcription factors (ptf1a and prox1) by qPCR. Our results showed that they were not affected at 10 dpf but upregulated at 18 dpf. After staining 15 dpf larvae with oil red we observed, in the mutants compared to their sibling wild type or heterozygous, significantly reduced accumulation of lipids. In addition, we found an increase of expression of genes involved in autophagy (atg5, atg7 and mTOR), and upregulation of casp9 and tp53 expression.With these results we thought that reduced viability was due to a problem in nutrient absorption and therefore starvation. We carried out two starvation experiments, a diet restriction from 10 to 15 dpf, and from 15 to 21 dpf. Unlike sbds mutants, mortality rates were not affected comparing to control groups in any of these experiments. However, genes related to lipid metabolism and autophagy were upregulated and histology showed a reduction in intestinal epithelium as well. Moreover, oil red staining showed lower lipid accumulation in starved fish as we observed in sbds mutants.With these results, we conclude sbds -null zebrafish showed signs of malnutrition and an effect in fatty acid-metabolism gene expression as seen in starved fish. Our results make it a highly relevant model to investigate new mechanistic hypotheses and develop new small molecule therapies for Shwachman-Diamond syndrome.1. Boocock GR, Morrison JA, Popovic M, et al. Mutations in SBDS are associated with Shwachman-Diamond syndrome. Nat Genet . 2003;33(1):97-101.2. Austin KM, Gupta ML, Jr., Coats SA, et al. Mitotic spindle destabilization and genomic instability in Shwachman-Diamond syndrome. J Clin Invest . 2008;118(4):1511-1518.3. Finch AJ, Hilcenko C, Basse N, et al. Uncoupling of GTP hydrolysis from eIF6 release on the ribosome causes Shwachman-Diamond syndrome. Genes Dev . 2011;25(9):917-929.4. Bezzerri V, Vella A, Calcaterra E, et al. New insights into the Shwachman-Diamond Syndrome-related haematological disorder: hyper-activation of mTOR and STAT3 in leukocytes. 2016;6:33165.5. Zhang S, Shi M, Hui CC, Rommens JM. Loss of the mouse ortholog of the Shwachman-Diamond syndrome gene (Sbds) results in early embryonic lethality. Mol Cell Biol . 2006;26(17):6656-6663. DisclosuresNo relevant conflicts of interest to declare.

Exploration of zebrafish larvae as an alternative whole-animal model for nephrotoxicity testing

Due to an increasing demand for testing of new and existing chemicals and legal restrictions for the use of animals, there is a strong need for alternative approaches to assess systemic toxicity. Embryonic and larval zebrafish (Danio rerio) are increasingly recognized as a promising alternative whole-animal model that may be able to overcome limitations of cell-based in vitro assays and bridge the gap between high-throughput in vitro screening and low-throughput in vivo tests in animals. Despite the relatively simple anatomical structure of the zebrafish larval kidney (pronephros) – composed of only two nephrons - the pronephros shares major functions and cell types with mammalian nephrons. Glomerular filtration begins at 48 h post fertilization. The aim of the present study was to investigate if early zebrafish larvae might be a suitable model for nephrotoxicity testing. On day 3 post fertilization, larval zebrafish were treated with selected nephrotoxins (aristolochic acid, cadmium chloride, potassium bromate, ochratoxin A, gentamicin) for 48 h. Histological evaluation of zebrafish larvae exposed to model nephrotoxins revealed tubule injury as evidenced by dilated tubules with loss of the brush border, tubule cell necrosis and disorganization of the tubular epithelium. These changes were most severe after treatment with gentamicin, which also impaired pronephros function as evidenced by reduced clearance of FITC-dextran. Whole-mount in situ hybridization showing loss of cdh17 expression revealed site-specific injury to the proximal tubule segment. Analysis of genes previously identified as novel biomarkers of kidney injury in mammals showed upregulation of the kidney injury marker genes heme oxygenase 1 (hmox1), clusterin (clu), secreted phosphoprotein/osteopontin (spp1), connective tissue growth factor (ctgf) and kim-1 (havcr-1) in response to nephrotoxin treatment, although the response of individual genes varied across compounds. Consistent with the severity of lesions and impaired kidney function, the most prominent gene expression changes occurred in larvae exposed to gentamicin. Overall, our results suggest that larval zebrafish may be a suitable alternative model organism for nephrotoxicity screening, yet further improvements and integration with quantitative in vitro to in vivo extrapolation will be needed to predict human toxicity.

Beyond PROX1: transcriptional, epigenetic, and noncoding RNA regulation of lymphatic identity and function.

The lymphatic vascular system acts as the major transportation highway of tissue fluids, and its activation or impairment is associated with a wide range of diseases. There has been increasing interest in understanding the mechanisms that control lymphatic vessel formation (lymphangiogenesis) and function in development and disease. Here, we discuss recent insights into new players whose identification has contributed to deciphering the lymphatic regulatory code. We reveal how lymphatic endothelial cells, the building blocks of lymphatic vessels, utilize their transcriptional, post-transcriptional, and epigenetic portfolio to commit to and maintain their vascular lineage identity and function, with a particular focus on development.

Identifying virulence determinants of multidrug-resistant Klebsiella pneumoniae in Galleria mellonella.

ABSTRACTInfections caused by Klebsiella pneumoniae are a major public health threat. Extensively drug-resistant and even pan-resistant strains have been reported. Understanding K. pneumoniae pathogenesis is hampered by the fact that murine models of infection offer limited resolution for non-hypervirulent strains which cause the majority of infections. The insect Galleria mellonella larva is a widely used alternative model organism for bacterial pathogens. We have performed genome-scale fitness profiling of a multidrug-resistant K. pneumoniae ST258 strain during infection of G. mellonella, to determine if this model is suitable for large-scale virulence factor discovery in this pathogen. Our results demonstrated a dominant role for surface polysaccharides in infection, with contributions from siderophores, cell envelope proteins, purine biosynthesis genes and additional genes of unknown function. Comparison with a hypervirulent strain, ATCC 43816, revealed substantial overlap in important infection-related genes, as well as additional putative virulence factors specific to ST258, reflecting strain-dependent fitness effects. Our analysis also identified a role for the metalloregulatory protein NfeR (YqjI) in virulence. Overall, this study offers new insight into the infection fitness landscape of K. pneumoniae, and provides a framework for using the highly flexible and easily scalable G. mellonella infection model to dissect molecular virulence mechanisms of bacterial pathogens.

Zebrafish as an Emerging Model for Dyslipidemia and Associated Diseases.

Dyslipidemia related diseases such as hyperlipidemia and atherosclerosis are the leading cause of death in humans. While cellular and molecular basis on the pathophysiology of dyslipidemia has been extensively investigated over decades, we still lack comprehensive understanding on the etiology of dyslipidemia due to the complexity and the innate multimodality of the diseases. While mouse has been the model organism of choice to investigate the pathophysiology of human dyslipidemia, zebrafish, a small freshwater fish which has traditionally used to study vertebrate development, has recently emerged as an alternative model organism. In this review, we will provide comprehensive perspective on zebrafish as a model organism for human dyslipidemia; we will discuss the attributes of zebrafish as a model, and compare the lipid metabolism in zebrafish and humans. In addition, we will summarize current landscape of zebrafish-based dyslipidemia research.

Rhesus macaques as a tractable physiological model of human ageing.

Research in the basic biology of ageing is increasingly identifying mechanisms and modifiers of ageing in short-lived organisms such as worms and mice. The ultimate goal of such work is to improve human health, particularly in the growing segment of the population surviving into old age. Thus far, few interventions have robustly transcended species boundaries in the laboratory, suggesting that changes in approach are needed to avoid costly failures in translational human research. In this review, we discuss both well-established and alternative model organisms for ageing research and outline how research in nonhuman primates is sorely needed, first, to translate findings from short-lived organisms to humans, and second, to understand key aspects of ageing that are unique to primate biology. We focus on rhesus macaques as a particularly promising model organism for ageing research owing to their social and physiological similarity to humans as well as the existence of key resources that have been developed for this species. As a case study, we compare gene regulatory signatures of ageing in the peripheral immune system between humans and rhesus macaques from a free-ranging study population in Cayo Santiago. We show that both mRNA expression and DNA methylation signatures of immune ageing are broadly shared between macaques and humans, indicating strong conservation of the trajectory of ageing in the immune system. We conclude with a review of key issues in the biology of ageing for which macaques and other nonhuman primates may uniquely contribute valuable insights, including the effects of social gradients on health and ageing. We anticipate that continuing research in rhesus macaques and other nonhuman primates will play a critical role in conjunction with the model organism and human biodemographic research in ultimately improving translational outcomes and extending health and longevity in our ageing population. This article is part of the theme issue 'Evolution of the primate ageing process'.

S30. SCHIZOPHRENIA IN A FISH: EFFECTS OF NMDA ANTAGONISM ON LOCOMOTOR BEHAVIOR AND SOCIAL INTERACTION IN ZEBRAFISH

BackgroundApplying cross-species approaches in animal preclinical studies of psychiatric disorders can minimize the overinterpretations often generated using specific strains or species in animal models of human conditions. Zebrafish is a model organism widely used in neuroscience research as an alternative to rodents, but protocols relevant to the symptoms and neurobiology of schizophrenia have not been fully established and validated in this species. MK-801, an NMDA receptor antagonist, is frequently used to recapitulate schizophrenia symptoms in rodent models. We thus aimed to evaluate the effects of a concentration curve of MK-801 on locomotor activity, social interaction, and neurochemical parameters related to oxidative stress in adult zebrafish.MethodsWild-type male and female zebrafish (50:50 ratio) were randomly allocated to 4 groups: control; 1 µM MK-801; 5 µM MK-801 or 10 µM MK-801 (n = 12). In the locomotor activity test animals were individually and sequentially placed in (1) a beaker with 200 mL of water for 20 min, (2) test aquarium for 30 min to assess basal locomotor activity, (3) beaker with water or MK-801 at the different concentrations for 20 min, and (4) test aquarium for 60 min. Locomotor and exploratory parameters (total distance traveled and upper zone time) were automatically analyzed using ANY-Maze software. In the social interaction test animals were individually exposed to water or MK-801 for 20 min and then placed for 7 min in a tank flanked by two identical tanks either empty or containing 10 zebrafish serving as social stimuli. Distance traveled was automatically tracked while social interaction time was manually and blindly scored using Boris software; only the last 5 minutes were analyzed. Oxidative damage in the brain was assessed by the levels of thiobarbituric acid reactive substances (TBARS). Data were analyzed by ANOVA followed by Tukey post hoc test.ResultsExposure to 5 µM MK-801 decreased the total distance traveled in the locomotor activity test. In the social interaction test, exposure to 5 and 10 µM MK-801 significantly increased the total distance traveled while reduced the time of social interaction with the stimulus animals. No differences in TBARS levels were found between the groups.DiscussionUnlike what is observed in rodents after MK-801 administration, zebrafish did not show hyperlocomotion at the concentrations tested. Other studies point to the context-dependent effect of this drug, as an increase in locomotor activity is only observed when animals are tested in a novel environment. In the social interaction test, on the other hand, animals were tested in a novel context with social stimulus and zebrafish exhibited hyperlocomotion and decreased social interaction, similar to what is observed in rodents. In contrast to chronic animal models and patients with schizophrenia, there were no differences in TBARS levels after acute exposure to MK-801. These preliminary results reinforce that zebrafish is an alternative model organism useful to the study of psychotic disorders. More behavioral and biochemical tests are needed to achieve reproducible tests and models to study multiple schizophrenia domains in zebrafish.

Porcine model for the study of sperm capacitation, fertilization and male fertility.

Mammalian fertilization remains a poorly understood event with the vast majority of studies done in the mouse model. The purpose of this review is to revise the current knowledge about semen deposition, sperm transport, sperm capacitation, gamete interactions and early embryonic development with a focus on the porcine model as a relevant, alternative model organism to humans. The review provides a thorough overview of post-ejaculation events inside the sow's reproductive tract including comparisons with humans and implications for human fertilization and assisted reproductive therapy (ART). Porcine methodology for sperm handling, preservation, in vitro capacitation, oocyte in vitro maturation, in vitro fertilization and intra-cytoplasmic sperm injection that are routinely used in pig research laboratories can be successfully translated into ART to treat human infertility. Last, but not least, new knowledge about mitochondrial inheritance in the pig can provide an insight into human mitochondrial diseases and new knowledge on polyspermy defense mechanisms could contribute to the development of new male contraceptives.

Isoprene Oxidation by the Gram-Negative Model bacterium Variovorax sp. WS11.

Plant-produced isoprene (2-methyl-1,3-butadiene) represents a significant portion of global volatile organic compound production, equaled only by methane. A metabolic pathway for the degradation of isoprene was first described for the Gram-positive bacterium Rhodococcus sp. AD45, and an alternative model organism has yet to be characterised. Here, we report the characterisation of a novel Gram-negative isoprene-degrading bacterium, Variovorax sp. WS11. Isoprene metabolism in this bacterium involves a plasmid-encoded iso metabolic gene cluster which differs from that found in Rhodococcus sp. AD45 in terms of organisation and regulation. Expression of iso metabolic genes is significantly upregulated by both isoprene and epoxyisoprene. The enzyme responsible for the initial oxidation of isoprene, isoprene monooxygenase, oxidises a wide range of alkene substrates in a manner which is strongly influenced by the presence of alkyl side-chains and differs from other well-characterised soluble diiron monooxygenases according to its response to alkyne inhibitors. This study presents Variovorax sp. WS11 as both a comparative and contrasting model organism for the study of isoprene metabolism in bacteria, aiding our understanding of the conservation of this biochemical pathway across diverse ecological niches.

Ageing differently: Sex-dependent ageing rates in Daphnia magna.

Ageing is defined as the gradual decline of normal physiological functions in a time-dependent manner. Significant progress has been made in characterising the regulatory processes involved in the mechanisms of ageing which would have been hindered without the use of model organisms. Use of alternative model organisms greatly diversifies our understanding of different factors underpinning the ageing process and the potential translation for human application. Unique characteristics make Daphnia an attractive model organism for research into mechanisms underlying ageing, such as transparent body, short generation time, well-characterised methylome, regenerative capabilities and available naturally occurring ecotypes. Most interestingly, genetically identical female and male Daphnia have evolved different average lifespans, providing a unique opportunity for understanding the underlying mechanisms of ageing and regulation of lifespan. Investigating sex differences in longevity could provide insight into principal mechanisms of ageing and lifespan regulation. In this study we provide evidence in support of establishing genetically identical female and male Daphnia as unique and valuable resources for research into mechanisms of ageing and begin to delineate the mechanisms involved in sex differences in lifespan. We identify significant differences between genders in physiological markers such as lifespan, growth rate, heart rate and swimming speed in addition to molecular markers such as lipid peroxidation product accumulation, thiol content decline and age-dependent decline in DNA damage repair efficiency. Overall, our data indicates that investigating sex differences in longevity in the clonal organism Daphnia under controlled laboratory conditions can provide insight into principal mechanisms of ageing and lifespan regulation.